1. Field of the Invention
The present invention relates to voice mail systems configured for providing messaging services for subscribers in a voice over Internet Protocol (IP) network according to H.323 protocol.
2. Description of the Related Art
The evolution of the public switched telephone network has resulted in a variety of voice applications and services that can be provided to individual subscribers and business subscribers. Such services include voice messaging systems that enable landline or wireless subscribers to record, playback, and forward voice mail messages. However, the ability to provide enhanced services to subscribers of the public switched telephone network is directly affected by the limitations of the public switched telephone network. In particular, the public switched telephone network operates according to a protocol that is specifically designed for the transport of voice signals; hence any modifications necessary to provide enhanced services can only be done by switch vendors that have sufficient know-how of the existing public switched telephone network infrastructure. Hence, the reliance on proprietary protocols and closed development environments by telecommunications equipment providers has limited service providers to vendor-specific implementations of voice and telephony services.
One particular problem in existing voice mail systems is the inability to provide more complex features for voice mail subscribers. For example, conventional voice mail systems are limited to allowing a voice mail subscriber to merely retrieve stored voice mail messages, and possibly forward a voice mail message to another voice mail subscriber within the same voice mail system. However, these conventional voice mail systems do not permit a voice mail subscriber to perform more advanced operations.
Assume that a voice mail subscriber calls into his or her voice mailbox to retrieve messages. During the retrieval of messages, the voice mail subscriber desires to return a call to a party that left the voice mail subscriber a message. Normally the voice mail subscriber would need to terminate the voice mail session and manually call back the party that left the message, resulting in substantial inconvenience to the voice mail subscriber. After completing the call with the party that left the message, the voice mail subscriber normally would need to call back into the voice mail system to access his or her mailbox. Hence the voice mail subscriber needs to endure the added inconvenience of calling back the voice mail system: this inconvenience in repeatedly hanging up and redialing the voice system and/or a party having left a message results in annoyance to the voice mail subscriber, as well as increased toll charges.
U.S. Pat. No. 5,857,013 to Yue et al. suggests the desirability of enabling a mobile telephone user to access his or her associated voice mail system and have the system automatically call a number of a person, having left a message, without leaving the voice mail service. Yue et al. merely suggests use of a Bell South service circuit node, available from AT&T network systems, where the system software is coded in the service logic language within a UNIX environment. Yue et al., however, provides no disclosure of how such a system would be implemented in a telephone network such as a mobile telephone system or the public switched telephone network.
Voice over IP technology is under development as part of an alternative open packet telephony communications network, distinct from the public (circuit switched) telephone network, capable of using packet switched networks for integrating voice, data, facsimile, and Internet services, and the like. New packet telephony voice services are being built from open standards such as The International Telecommunications Union (ITU) Recommendation H.323. Recommendation H.323 defines the components, procedures, and protocols necessary to provide audiovisual communications on local area networks. Recommendation H.323 is based on the Real Time Protocol/Control Protocol (RTP/RTCP) of the Internet Engineering Task Force (IETF), and applies to either point-to-point or multipoint sessions, and references many other ITU recommendations, including H.225 and H.245. Recommendation H.225 specifies messages for call control including signaling, registration and admissions, and packetization/synchronization of media streams. Recommendation H.245 specifies messages for opening and closing channels for media streams, and other commands, requests and indications.
Although voice over IP systems are being deployed to provide point-to-point voice communications services, the current H.323 standard does not provide a direct means for enabling a voice mail subscriber to place an outbound call from a voice mail system, and then return to the voice mailbox after call completion.